Prior art reference may be made to U.S. Pat. No. 4,221,297, titled: “Electronic fruit grading machines,” wherein is described an electronic fruit grading machine consisting of an endless chain having positioning rollers or bars which rotate and on which the fruit coming from a hopper is positioned in rows. The grading machine includes an electronic apparatus capable of detecting surface marks or defects in the fruit which is situated on the bars. The fruit is arranged in transverse rows and is displaced at a certain speed under a standard television camera. The feed of the fruit from the hopper to the endless chain is carried out by a cylindrical drum acting as a feeding device. On the surface of the cylindrical drum are rows of holes, and adjacent each hole is provided a wedge, one face of which follows the prolongation of a radius of the cylindrical drum and is arranged for the expulsion of extra fruit adhered to the periphery of the cylindrical drum.
The drawback of this machine of U.S. Pat. No. 4,221,297, is that the grading is done only in two categories namely, accepted or rejected. Its inspection system is not meticulous enough to grade them in more than two categories.
Reference may also be made to U.S. Pat. No. 4,687,107, wherein a machine titled: ‘Apparatus for sizing and sorting of articles’ has been described. This apparatus sorts articles according to any combination of plural criteria, including volume or diameter, length, shape, weight, color, density and surface quality. A light sensitive dynamic random access memory and novel processing circuitry are utilized for providing indications of the article's volume, diameter and length.
The drawback in this machine of U.S. Pat. No. 4,687,107, is that complete surface inspection like looking for possible bruises etc. is not done and the fruits are carried by rollers, where the color sensor and the surface inspector sees a part of the surface, on which the operator has no control. This way, if the fruit is not oriented properly, the machine may end up seeing the stem part of the fruit, on the basis of such vision a fruit cannot be judged.
A further prior art reference may be made to U.S. Pat. No. 6,079,542, titled: ‘Object sorter and sizer’ wherein an apparatus and methods for sorting objects such as fruits, by categories, such as size, shape, weight and color have been described. The object sorting system includes a product presentation device with a floating portion and a subframe pivotally connected to a frame link driven by a chain. The product presentation device and frame link operate with a latch so that the product presentation device can move objects through the system to be sorted and deposit the objects at an appropriate job station. The floating portion of the product presentation device allows accurate determination of object weights. The product presentation device can also be married to or divorced from wheels which are used to turn the object before a viewer for sorting based on visual characteristics. Because the wheels can be divorced from the product presentation device, objects can be deposited more gently in collection bins at the drop stations. The system may use belt driven or roller driven pre-singulation to assure that only one object is placed in a product presentation device. The system has independently driven chain drives for the wheels and the product presentation devices. Chain phasing is employed on either the chain drive for the wheels or the product presentation device to maintain appropriate spacing between the wheels and the product presentation device, thereby reducing wear and tear on the system and its components.
The major drawback of the above said U.S. Pat. No. 6,079,542, titled: ‘Object sorter and sizer’ is that this machine rotates but does not orient the fruit which results in taking photographs of unwanted parts of the fruit, thereby increasing the load and cost of image processing.
As a consequence to the hitherto known prior art as described herein above, it is clear that there is a definite need for providing an orientation unit for fruit sorting and grading machines which will enable image sensing in a favorable manner.